Let me start by apologizing for not providing the whole story on the problem on the trouble I am having with my 1987 Johnson V4 88hp SPL. I am proving the whole history now along with some results from tests I did this morning. I also want to apologize for starting a new thread but I didn't seem to be getting any responses after providing the the whole story yesterday. I thought maybe it was too far down in the forum. Anyways here is the story:
Last fall my son bought the boat and it wasn't running right so he gave up and gave it to me. The original problem was that the engine would run fine all the time at idle. But once you put it in gear it would lose all power after about 5 minutes and never regain it till the next time you went out and then the same thing would happen. So here is what I did and found:
1) Replaced fuel pump. It was a cheap shot at solving the problem. The problem still existed.
2) Rebuilt carbs. Didn't help
3) Did both a warm and cold compression test. If I remember right all 4 cylinders were about 135lbs.
4) Did a spark plug gap test on all 4 cylinders. All 4 had a nice blue spark that jumped the gap.
By now it was winter so I decided to replace the deck which was soft in a few spots. Its at this time that I found that the vent line for the inboard gas tank was bloated and falling apart. So I replaced the vent line and waited for spring.
This spring I took it out and it ran like a champ. I have had it out at least 4 or 5 times and it always ran great until this last weekend when it started acting up and had no power when in gear.
So while I was out on the river I did the following:
1) Removed vent line from gas tank but no difference which I kinda already knew.
2) I put a spark plug monitor on each of the two top plugs since they were the ones that were wet.
It was pretty bright out so I put my hat over the tester and I could see that the light was pulsing on both top
cylinders. (didn't check the bottom two cylinders since the plugs were a brownish color and dry)
3) I then took the carb cover off to look at them while the engine was running. I could see gas flowing into the carbs.
Not sure if this is good or bad. I did see some white greasy substance on the bottom of what I think they call air
horns. The choke plates and the rest of what I could see were nice and shiny.
I then brought the boat in. Here are my plans for shooting the problem. Please let me know if I'm doing the right steps in the right order:
- Gonna redo the compression test just for sanity's sake. 135lbs on all 4 cylinders with engine warm
- Redo the spark gap test again just to make sure all 4 coils and 2 power paks are still working. All 4 coils were putting out a nice blue spark and had no trouble jumping a 1/2 inch gap
- Ran engine with inline spark plug testers All 4 testers were lighting up as the engine ran
- So I guess all that leaves is to pull the top carb and check the jets and make sure the float isn't sticking and blow it all out.
- The white greasy substance on the bottom of what I think they call air horns has me puzzled. Never saw that on the last Johnson motor I had which was a 1972 50hp 2 cylinder.
Am I missing something or is this the right way to precede? I want to thank all that reply. This is so frustrating.
Jerry
Last fall my son bought the boat and it wasn't running right so he gave up and gave it to me. The original problem was that the engine would run fine all the time at idle. But once you put it in gear it would lose all power after about 5 minutes and never regain it till the next time you went out and then the same thing would happen. So here is what I did and found:
1) Replaced fuel pump. It was a cheap shot at solving the problem. The problem still existed.
2) Rebuilt carbs. Didn't help
3) Did both a warm and cold compression test. If I remember right all 4 cylinders were about 135lbs.
4) Did a spark plug gap test on all 4 cylinders. All 4 had a nice blue spark that jumped the gap.
By now it was winter so I decided to replace the deck which was soft in a few spots. Its at this time that I found that the vent line for the inboard gas tank was bloated and falling apart. So I replaced the vent line and waited for spring.
This spring I took it out and it ran like a champ. I have had it out at least 4 or 5 times and it always ran great until this last weekend when it started acting up and had no power when in gear.
So while I was out on the river I did the following:
1) Removed vent line from gas tank but no difference which I kinda already knew.
2) I put a spark plug monitor on each of the two top plugs since they were the ones that were wet.
It was pretty bright out so I put my hat over the tester and I could see that the light was pulsing on both top
cylinders. (didn't check the bottom two cylinders since the plugs were a brownish color and dry)
3) I then took the carb cover off to look at them while the engine was running. I could see gas flowing into the carbs.
Not sure if this is good or bad. I did see some white greasy substance on the bottom of what I think they call air
horns. The choke plates and the rest of what I could see were nice and shiny.
I then brought the boat in. Here are my plans for shooting the problem. Please let me know if I'm doing the right steps in the right order:
- Gonna redo the compression test just for sanity's sake. 135lbs on all 4 cylinders with engine warm
- Redo the spark gap test again just to make sure all 4 coils and 2 power paks are still working. All 4 coils were putting out a nice blue spark and had no trouble jumping a 1/2 inch gap
- Ran engine with inline spark plug testers All 4 testers were lighting up as the engine ran
- So I guess all that leaves is to pull the top carb and check the jets and make sure the float isn't sticking and blow it all out.
- The white greasy substance on the bottom of what I think they call air horns has me puzzled. Never saw that on the last Johnson motor I had which was a 1972 50hp 2 cylinder.
Am I missing something or is this the right way to precede? I want to thank all that reply. This is so frustrating.
Jerry